drivers/iio/proximity/as3935.c

   1 /*
   2  * as3935.c - Support for AS3935 Franklin lightning sensor
   3  *
   4  * Copyright (C) 2014 Matt Ranostay <mranostay@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/delay.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/mutex.h>
  24 #include <linux/err.h>
  25 #include <linux/irq.h>
  26 #include <linux/gpio.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/iio/iio.h>
  29 #include <linux/iio/sysfs.h>
  30 #include <linux/iio/trigger.h>
  31 #include <linux/iio/trigger_consumer.h>
  32 #include <linux/iio/buffer.h>
  33 #include <linux/iio/triggered_buffer.h>
  34 #include <linux/of_gpio.h>
  35
  36
  37 #define AS3935_AFE_GAIN         0x00
  38 #define AS3935_AFE_MASK         0x3F
  39 #define AS3935_AFE_GAIN_MAX     0x1F
  40 #define AS3935_AFE_PWR_BIT      BIT(0)
  41
  42 #define AS3935_INT              0x03
  43 #define AS3935_INT_MASK         0x0f
  44 #define AS3935_EVENT_INT        BIT(3)
  45 #define AS3935_NOISE_INT        BIT(0)
  46
  47 #define AS3935_DATA             0x07
  48 #define AS3935_DATA_MASK        0x3F
  49
  50 #define AS3935_TUNE_CAP         0x08
  51 #define AS3935_CALIBRATE        0x3D
  52
  53 #define AS3935_READ_DATA        BIT(14)
  54 #define AS3935_ADDRESS(x)       ((x) << 8)
  55
  56 #define MAX_PF_CAP              120
  57 #define TUNE_CAP_DIV            8
  58
  59 struct as3935_state {
  60         struct spi_device *spi;
  61         struct iio_trigger *trig;
  62         struct mutex lock;
  63         struct delayed_work work;
  64
  65         u32 tune_cap;
  66         u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
  67         u8 buf[2] ____cacheline_aligned;
  68 };
  69
  70 static const struct iio_chan_spec as3935_channels[] = {
  71         {
  72                 .type           = IIO_PROXIMITY,
  73                 .info_mask_separate =
  74                         BIT(IIO_CHAN_INFO_RAW) |
  75                         BIT(IIO_CHAN_INFO_PROCESSED) |
  76                         BIT(IIO_CHAN_INFO_SCALE),
  77                 .scan_index     = 0,
  78                 .scan_type = {
  79                         .sign           = 'u',
  80                         .realbits       = 6,
  81                         .storagebits    = 8,
  82                 },
  83         },
  84         IIO_CHAN_SOFT_TIMESTAMP(1),
  85 };
  86
  87 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
  88 {
  89         u8 cmd;
  90         int ret;
  91
  92         cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
  93         ret = spi_w8r8(st->spi, cmd);
  94         if (ret < 0)
  95                 return ret;
  96         *val = ret;
  97
  98         return 0;
  99 }
 100
 101 static int as3935_write(struct as3935_state *st,
 102                                 unsigned int reg,
 103                                 unsigned int val)
 104 {
 105         u8 *buf = st->buf;
 106
 107         buf[0] = AS3935_ADDRESS(reg) >> 8;
 108         buf[1] = val;
 109
 110         return spi_write(st->spi, buf, 2);
 111 }
 112
 113 static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
 114                                         struct device_attribute *attr,
 115                                         char *buf)
 116 {
 117         struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
 118         int val, ret;
 119
 120         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 121         if (ret)
 122                 return ret;
 123         val = (val & AS3935_AFE_MASK) >> 1;
 124
 125         return sprintf(buf, "%d\n", val);
 126 }
 127
 128 static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
 129                                         struct device_attribute *attr,
 130                                         const char *buf, size_t len)
 131 {
 132         struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
 133         unsigned long val;
 134         int ret;
 135
 136         ret = kstrtoul((const char *) buf, 10, &val);
 137         if (ret)
 138                 return -EINVAL;
 139
 140         if (val > AS3935_AFE_GAIN_MAX)
 141                 return -EINVAL;
 142
 143         as3935_write(st, AS3935_AFE_GAIN, val << 1);
 144
 145         return len;
 146 }
 147
 148 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
 149         as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
 150
 151
 152 static struct attribute *as3935_attributes[] = {
 153         &iio_dev_attr_sensor_sensitivity.dev_attr.attr,
 154         NULL,
 155 };
 156
 157 static struct attribute_group as3935_attribute_group = {
 158         .attrs = as3935_attributes,
 159 };
 160
 161 static int as3935_read_raw(struct iio_dev *indio_dev,
 162                            struct iio_chan_spec const *chan,
 163                            int *val,
 164                            int *val2,
 165                            long m)
 166 {
 167         struct as3935_state *st = iio_priv(indio_dev);
 168         int ret;
 169
 170
 171         switch (m) {
 172         case IIO_CHAN_INFO_PROCESSED:
 173         case IIO_CHAN_INFO_RAW:
 174                 *val2 = 0;
 175                 ret = as3935_read(st, AS3935_DATA, val);
 176                 if (ret)
 177                         return ret;
 178
 179                 if (m == IIO_CHAN_INFO_RAW)
 180                         return IIO_VAL_INT;
 181
 182                 /* storm out of range */
 183                 if (*val == AS3935_DATA_MASK)
 184                         return -EINVAL;
 185
 186                 if (m == IIO_CHAN_INFO_PROCESSED)
 187                         *val *= 1000;
 188                 break;
 189         case IIO_CHAN_INFO_SCALE:
 190                 *val = 1000;
 191                 break;
 192         default:
 193                 return -EINVAL;
 194         }
 195
 196         return IIO_VAL_INT;
 197 }
 198
 199 static const struct iio_info as3935_info = {
 200         .driver_module = THIS_MODULE,
 201         .attrs = &as3935_attribute_group,
 202         .read_raw = &as3935_read_raw,
 203 };
 204
 205 static irqreturn_t as3935_trigger_handler(int irq, void *private)
 206 {
 207         struct iio_poll_func *pf = private;
 208         struct iio_dev *indio_dev = pf->indio_dev;
 209         struct as3935_state *st = iio_priv(indio_dev);
 210         int val, ret;
 211
 212         ret = as3935_read(st, AS3935_DATA, &val);
 213         if (ret)
 214                 goto err_read;
 215
 216         st->buffer[0] = val & AS3935_DATA_MASK;
 217         iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
 218                                            iio_get_time_ns(indio_dev));
 219 err_read:
 220         iio_trigger_notify_done(indio_dev->trig);
 221
 222         return IRQ_HANDLED;
 223 }
 224
 225 static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
 226         .owner = THIS_MODULE,
 227 };
 228
 229 static void as3935_event_work(struct work_struct *work)
 230 {
 231         struct as3935_state *st;
 232         int val;
 233         int ret;
 234
 235         st = container_of(work, struct as3935_state, work.work);
 236
 237         ret = as3935_read(st, AS3935_INT, &val);
 238         if (ret) {
 239                 dev_warn(&st->spi->dev, "read error\n");
 240                 return;
 241         }
 242
 243         val &= AS3935_INT_MASK;
 244
 245         switch (val) {
 246         case AS3935_EVENT_INT:
 247                 iio_trigger_poll_chained(st->trig);
 248                 break;
 249         case AS3935_NOISE_INT:
 250                 dev_warn(&st->spi->dev, "noise level is too high\n");
 251                 break;
 252         }
 253 }
 254
 255 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
 256 {
 257         struct iio_dev *indio_dev = private;
 258         struct as3935_state *st = iio_priv(indio_dev);
 259
 260         /*
 261          * Delay work for >2 milliseconds after an interrupt to allow
 262          * estimated distance to recalculated.
 263          */
 264
 265         schedule_delayed_work(&st->work, msecs_to_jiffies(3));
 266
 267         return IRQ_HANDLED;
 268 }
 269
 270 static void calibrate_as3935(struct as3935_state *st)
 271 {
 272         /* mask disturber interrupt bit */
 273         as3935_write(st, AS3935_INT, BIT(5));
 274
 275         as3935_write(st, AS3935_CALIBRATE, 0x96);
 276         as3935_write(st, AS3935_TUNE_CAP,
 277                 BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
 278
 279         mdelay(2);
 280         as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
 281 }
 282
 283 #ifdef CONFIG_PM_SLEEP
 284 static int as3935_suspend(struct device *dev)
 285 {
 286         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 287         struct as3935_state *st = iio_priv(indio_dev);
 288         int val, ret;
 289
 290         mutex_lock(&st->lock);
 291         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 292         if (ret)
 293                 goto err_suspend;
 294         val |= AS3935_AFE_PWR_BIT;
 295
 296         ret = as3935_write(st, AS3935_AFE_GAIN, val);
 297
 298 err_suspend:
 299         mutex_unlock(&st->lock);
 300
 301         return ret;
 302 }
 303
 304 static int as3935_resume(struct device *dev)
 305 {
 306         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 307         struct as3935_state *st = iio_priv(indio_dev);
 308         int val, ret;
 309
 310         mutex_lock(&st->lock);
 311         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 312         if (ret)
 313                 goto err_resume;
 314         val &= ~AS3935_AFE_PWR_BIT;
 315         ret = as3935_write(st, AS3935_AFE_GAIN, val);
 316
 317         calibrate_as3935(st);
 318
 319 err_resume:
 320         mutex_unlock(&st->lock);
 321
 322         return ret;
 323 }
 324
 325 static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
 326 #define AS3935_PM_OPS (&as3935_pm_ops)
 327
 328 #else
 329 #define AS3935_PM_OPS NULL
 330 #endif
 331
 332 static int as3935_probe(struct spi_device *spi)
 333 {
 334         struct iio_dev *indio_dev;
 335         struct iio_trigger *trig;
 336         struct as3935_state *st;
 337         struct device_node *np = spi->dev.of_node;
 338         int ret;
 339
 340         /* Be sure lightning event interrupt is specified */
 341         if (!spi->irq) {
 342                 dev_err(&spi->dev, "unable to get event interrupt\n");
 343                 return -EINVAL;
 344         }
 345
 346         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 347         if (!indio_dev)
 348                 return -ENOMEM;
 349
 350         st = iio_priv(indio_dev);
 351         st->spi = spi;
 352
 353         spi_set_drvdata(spi, indio_dev);
 354         mutex_init(&st->lock);
 355         INIT_DELAYED_WORK(&st->work, as3935_event_work);
 356
 357         ret = of_property_read_u32(np,
 358                         "ams,tuning-capacitor-pf", &st->tune_cap);
 359         if (ret) {
 360                 st->tune_cap = 0;
 361                 dev_warn(&spi->dev,
 362                         "no tuning-capacitor-pf set, defaulting to %d",
 363                         st->tune_cap);
 364         }
 365
 366         if (st->tune_cap > MAX_PF_CAP) {
 367                 dev_err(&spi->dev,
 368                         "wrong tuning-capacitor-pf setting of %d\n",
 369                         st->tune_cap);
 370                 return -EINVAL;
 371         }
 372
 373         indio_dev->dev.parent = &spi->dev;
 374         indio_dev->name = spi_get_device_id(spi)->name;
 375         indio_dev->channels = as3935_channels;
 376         indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
 377         indio_dev->modes = INDIO_DIRECT_MODE;
 378         indio_dev->info = &as3935_info;
 379
 380         trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
 381                                       indio_dev->name, indio_dev->id);
 382
 383         if (!trig)
 384                 return -ENOMEM;
 385
 386         st->trig = trig;
 387         trig->dev.parent = indio_dev->dev.parent;
 388         iio_trigger_set_drvdata(trig, indio_dev);
 389         trig->ops = &iio_interrupt_trigger_ops;
 390
 391         ret = iio_trigger_register(trig);
 392         if (ret) {
 393                 dev_err(&spi->dev, "failed to register trigger\n");
 394                 return ret;
 395         }
 396
 397         ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
 398                 &as3935_trigger_handler, NULL);
 399
 400         if (ret) {
 401                 dev_err(&spi->dev, "cannot setup iio trigger\n");
 402                 goto unregister_trigger;
 403         }
 404
 405         calibrate_as3935(st);
 406
 407         ret = devm_request_irq(&spi->dev, spi->irq,
 408                                 &as3935_interrupt_handler,
 409                                 IRQF_TRIGGER_RISING,
 410                                 dev_name(&spi->dev),
 411                                 indio_dev);
 412
 413         if (ret) {
 414                 dev_err(&spi->dev, "unable to request irq\n");
 415                 goto unregister_buffer;
 416         }
 417
 418         ret = iio_device_register(indio_dev);
 419         if (ret < 0) {
 420                 dev_err(&spi->dev, "unable to register device\n");
 421                 goto unregister_buffer;
 422         }
 423         return 0;
 424
 425 unregister_buffer:
 426         iio_triggered_buffer_cleanup(indio_dev);
 427
 428 unregister_trigger:
 429         iio_trigger_unregister(st->trig);
 430
 431         return ret;
 432 }
 433
 434 static int as3935_remove(struct spi_device *spi)
 435 {
 436         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 437         struct as3935_state *st = iio_priv(indio_dev);
 438
 439         iio_device_unregister(indio_dev);
 440         iio_triggered_buffer_cleanup(indio_dev);
 441         iio_trigger_unregister(st->trig);
 442
 443         return 0;
 444 }
 445
 446 static const struct of_device_id as3935_of_match[] = {
 447         { .compatible = "ams,as3935", },
 448         { /* sentinel */ },
 449 };
 450 MODULE_DEVICE_TABLE(of, as3935_of_match);
 451
 452 static const struct spi_device_id as3935_id[] = {
 453         {"as3935", 0},
 454         {},
 455 };
 456 MODULE_DEVICE_TABLE(spi, as3935_id);
 457
 458 static struct spi_driver as3935_driver = {
 459         .driver = {
 460                 .name   = "as3935",
 461                 .of_match_table = of_match_ptr(as3935_of_match),
 462                 .pm     = AS3935_PM_OPS,
 463         },
 464         .probe          = as3935_probe,
 465         .remove         = as3935_remove,
 466         .id_table       = as3935_id,
 467 };
 468 module_spi_driver(as3935_driver);
 469
 470 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
 471 MODULE_DESCRIPTION("AS3935 lightning sensor");
 472 MODULE_LICENSE("GPL");